drm/nouveau/debugfs: Replace five seq_printf() calls by seq_puts() in nouveau_debugfs_pstate_get()

Five strings which did not contain a data format specification should
be put into a sequence. Thus use the corresponding function “seq_puts”.

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Signed-off-by: Karol Herbst <kherbst@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/bdee7e41-094a-91d1-3f6f-56df402d70b7@web.de